The prior art of anti-bird perching or roosting devices was based on one of several approaches to deter birds from landing. These approaches were either used alone, or in combination one with the other. The approaches may be divided into a number of categories:                Magnetic        Optical        Sloped Surface        Mechanical: Cables        Unstable perch        Projections        Chemical        
Several inventors based their devices on the principle of creating a variable magnetic field. This is based on the theory that a magnetic field tends to repel birds. It is believed that birds have a biological instinctive ability to sense the presence of a magnetic field and that the field deters them. U.S. Pat. Nos. 5,884,426 to Ishida; 5,836,114 and 5,918,404 to Ohba are all based on this magnetic approach.
Another approach believes that birds can be deterred by optically frightening them. In U.S. Pat. No. 4,269,008 to Assouline, the inventor utilizes an optical device to frighten the birds.
Yet another approach is to incline the surface exposed to the birds to dissuade them from landing, since the birds desire a horizontal landing surface. In U.S. Pat. No. 5,913,780 to Georgen, there is disclosed a triangular hollow section, whose upper surface is inclined sufficiently to deter the birds.
Other inventors have utilized a cable, or series of parallel cables, running above the surface of interest to interfere with the birds' attempts at landing. In U.S. Pat. No. 5,092,088 to Way, and U.S. Pat. No. 5,713,160 to Heron, the inventors base their devices on this approach.
Destabilizing the exposed perching surface is seen as another way of deterring birds. In U.S. Pat. No. 5,497,585 to Engler, there is disclosed a device having a cable above the surface to be protected and a plurality of rotatable rings on the cable. The dimensions of the rings are such that when birds tried to perch they unbalanced the rings.
A popular method utilizes a base with spikes mounted either perpendicularly, or at various angles with the base. When the birds try to perch, the spikes prick them, thus deterring them. In U.S. Pat. No. 5,400,552 to Negre, there is disclosed a polymethylmethacrylate base, with spikes fitted perpendicularly. This configuration is thought to be less effective because over a period of time, bird feces fills in the gaps between the spikes and then the birds can freely perch.
In U.S. Pat. No. 5,167,099 to Nelson, there is disclosed a plurality of comb-like members each having comb teeth, mounted above the surface to be protected, to deter the birds. This device seems to be costly in terms of production cost.
In U.S. Pat. No. 5,974,998 to Gregg III, there is disclosed a specific solution to the specific problem of preventing birds from landing atop a masthead. The inventor uses upstanding posts on whose upper ends are positioned a plurality of rods. The post is hauled into position with its head above the masthead.
In U.S. Pat. No. 5,691,032 to Trueblood et al, the inventors proposed using a continuous, filled, base strip, in which a plurality of repellant arms is punched into the base strip. This device appears somewhat hazardous to install, as the repellant arms seem to be quite jagged. In addition, the continuous, filled, base strip seems inconvenient to secure to the surface, to be protected.
In U.S. Pat. No. 5,606,830 to Townsend, Jr. et al, the inventors use two vertically inclined panes of open rectangular wire-grid fencing, attached to one another, via hinges. Wire material, above the hinge points, creates upwardly projecting wire prongs. In this device, the protection afforded the surface is limited, as the spikes are almost vertical.
In U.S. Pat. No. 5,253,444 to Donoho et al, there is disclosed a device having a base member and a plurality of top members, each of which holds a plurality of prongs. The device appears to be rigid in construction, which may hinder installation and hamper adaptation to the changing needs of the user.
In addition, there are several chemical bird anti-roosting preparations. These tend to make the surface of the windowsill, etc., sticky. Consequently, dust and other filth adhere to the said surface in a short period of time, rendering the chemical preparation useless. The surface becomes accessible to the birds, once again.
Based on a review of the prior art, it becomes quite evident that each of the approaches employed in the past suffered from shortcomings of some sort or another. In some instances, such as the devices based on magnetic field and optical determent, the effectivity of the devices has not been firmly established. Devices using cables and the like, mounted above the surface of interest, demand a system of supports, which complicate the solution. The approach using a base element coupled with vertically oriented projections would seem less efficient, as bird feces will eventually fill in the gaps between the projections. Continuous, filled, base strip elements would seem to be cumbersome in installation and less given to easy dimensional adaptation.
Therefore, it would be desirable to provide a new anti-bird perching device, which overcomes the shortcomings of the prior art. The device should be lightweight and flexible, to facilitate installation. Also, if the top-element spikes are easily configurable, the device will enable the user to enjoy maximum protection against birds.